The root interface for accessing a Spring bean container.
This is the basic client view of a bean container;
further interfaces such as ListableBeanFactory and
ConfigurableBeanFactory
are available for specific purposes.

This interface is implemented by objects that hold a number of bean definitions,
each uniquely identified by a String name. Depending on the bean definition,
the factory will return either an independent instance of a contained object
(the Prototype design pattern), or a single shared instance (a superior
alternative to the Singleton design pattern, in which the instance is a
singleton in the scope of the factory). Which type of instance will be returned
depends on the bean factory configuration: the API is the same. Since Spring
2.0, further scopes are available depending on the concrete application
context (e.g. "request" and "session" scopes in a web environment).

The point of this approach is that the BeanFactory is a central registry
of application components, and centralizes configuration of application
components (no more do individual objects need to read properties files,
for example). See chapters 4 and 11 of "Expert One-on-One J2EE Design and
Development" for a discussion of the benefits of this approach.

Note that it is generally better to rely on Dependency Injection
("push" configuration) to configure application objects through setters
or constructors, rather than use any form of "pull" configuration like a
BeanFactory lookup. Spring's Dependency Injection functionality is
implemented using this BeanFactory interface and its subinterfaces.

Normally a BeanFactory will load bean definitions stored in a configuration
source (such as an XML document), and use the org.springframework.beans
package to configure the beans. However, an implementation could simply return
Java objects it creates as necessary directly in Java code. There are no
constraints on how the definitions could be stored: LDAP, RDBMS, XML,
properties file, etc. Implementations are encouraged to support references
amongst beans (Dependency Injection).

In contrast to the methods in ListableBeanFactory, all of the
operations in this interface will also check parent factories if this is a
HierarchicalBeanFactory. If a bean is not found in this factory instance,
the immediate parent factory will be asked. Beans in this factory instance
are supposed to override beans of the same name in any parent factory.

Field Detail

FACTORY_BEAN_PREFIX

Used to dereference a FactoryBean instance and distinguish it from
beans created by the FactoryBean. For example, if the bean named
myJndiObject is a FactoryBean, getting &myJndiObject
will return the factory, not the instance returned by the factory.

getBean

Return an instance, which may be shared or independent, of the specified bean.

Behaves the same as getBean(String), but provides a measure of type
safety by throwing a BeanNotOfRequiredTypeException if the bean is not of the
required type. This means that ClassCastException can't be thrown on casting
the result correctly, as can happen with getBean(String).

Translates aliases back to the corresponding canonical bean name.
Will ask the parent factory if the bean cannot be found in this factory instance.

Parameters:

name - the name of the bean to retrieve

requiredType - type the bean must match. Can be an interface or superclass
of the actual class, or null for any match. For example, if the value
is Object.class, this method will succeed whatever the class of the
returned instance.

getBean

Return the bean instance that uniquely matches the given object type, if any.

Parameters:

requiredType - type the bean must match; can be an interface or superclass.
null is disallowed.

This method goes into ListableBeanFactory by-type lookup territory
but may also be translated into a conventional by-name lookup based on the name
of the given type. For more extensive retrieval operations across sets of beans,
use ListableBeanFactory and/or BeanFactoryUtils.

containsBean

Does this bean factory contain a bean definition or externally registered singleton
instance with the given name?

If the given name is an alias, it will be translated back to the corresponding
canonical bean name.

If this factory is hierarchical, will ask any parent factory if the bean cannot
be found in this factory instance.

If a bean definition or singleton instance matching the given name is found,
this method will return true whether the named bean definition is concrete
or abstract, lazy or eager, in scope or not. Therefore, note that a true
return value from this method does not necessarily indicate that getBean(java.lang.String)
will be able to obtain an instance for the same name.

Parameters:

name - the name of the bean to query

Returns:

whether a bean with the given name is present

isSingleton

Note: This method returning false does not clearly indicate
independent instances. It indicates non-singleton instances, which may correspond
to a scoped bean as well. Use the isPrototype(java.lang.String) operation to explicitly
check for independent instances.

Translates aliases back to the corresponding canonical bean name.
Will ask the parent factory if the bean cannot be found in this factory instance.

isPrototype

Note: This method returning false does not clearly indicate
a singleton object. It indicates non-independent instances, which may correspond
to a scoped bean as well. Use the isSingleton(java.lang.String) operation to explicitly
check for a shared singleton instance.

Translates aliases back to the corresponding canonical bean name.
Will ask the parent factory if the bean cannot be found in this factory instance.

isTypeMatch

Check whether the bean with the given name matches the specified type.
More specifically, check whether a getBean(java.lang.String) call for the given name
would return an object that is assignable to the specified target type.

Translates aliases back to the corresponding canonical bean name.
Will ask the parent factory if the bean cannot be found in this factory instance.

Parameters:

name - the name of the bean to query

targetType - the type to match against

Returns:

true if the bean type matches,
false if it doesn't match or cannot be determined yet